Nuclear medical diagnosis apparatus and method for routine maintenance and inspection of nuclear medical diagnosis apparatus

Abstract

This nuclear medical diagnosis apparatus acquires a normalization factor based on reference data of a reference object to be measured, acquires a mutual calibration factor using at least a part of the reference data, and calculates radioactive concentration of the reference object to be measured.

The invention claimed is: 
     
       1. A nuclear medical diagnosis apparatus comprising:
 a plurality of detectors that detects annihilation radiation emitted from a reference object to be measured; 
 a data acquisition unit that acquires reference data of the reference object to be measured based on a result of detecting, by the plurality of detectors, the annihilation radiation emitted from the reference object to be measured; 
 a normalization unit that acquires a normalization factor for normalizing deviations of detection efficiencies among the plurality of detectors based on the reference data; 
 a calibration unit that applies the normalization factor to at least a part of the reference data used for acquisition of the normalization factor to acquire a mutual calibration factor for calibrating a pixel value of a reconstructed image of the reference object to be measured to radioactive concentration of the reference object to be measured; and 
 a quantitative value confirmation unit that compares radioactive concentration of the reference object to be measured calculated from a pixel value of an image of the reference object to be measured acquired by applying each of the normalization factor and the mutual calibration factor to at least a part of the reference data used for acquisition of the normalization factor with a quantitative value of the radioactive concentration of the reference object to be measured. 
 
     
     
       2. The nuclear medical diagnosis apparatus according to  claim 1 , wherein the data acquisition unit acquires the reference data by performing measurement once. 
     
     
       3. The nuclear medical diagnosis apparatus according to  claim 1 , wherein
 the calibration unit designates calibration data used for image reconstruction corresponding to a first area which is a part of the reference data and acquires the mutual calibration factor by applying the normalization factor to the calibration data to reconstruct the image, and 
 the quantitative value confirmation unit designates confirmation data corresponding to a second area which is apart of the reference data and calculates radioactive concentration of the reference object to be measured by applying each of the normalization factor and the mutual calibration factor to the confirmation data. 
 
     
     
       4. The nuclear medical diagnosis apparatus according to  claim 3 , wherein the calibration unit is configured to designate pieces of calibration data corresponding to a plurality of different first areas in the reference data, respectively, to acquire a plurality of mutual calibration factors corresponding to the plurality of pieces of calibration data, respectively. 
     
     
       5. The nuclear medical diagnosis apparatus according to  claim 3 , wherein the quantitative value confirmation unit is configured to designate pieces of confirmation data corresponding to a plurality of different second areas in the reference data, respectively, to calculate radioactive concentrations of the reference object to be measured corresponding to the plurality of pieces of confirmation data, respectively. 
     
     
       6. The nuclear medical diagnosis apparatus according to  claim 1 , wherein the normalization unit is configured to determine that a normalization factor acquired this time is valid when a difference between the normalization factor acquired this time and a normalization factor acquired at a previous time is within a first ratio of the normalization factor acquired at the previous time, the calibration unit is configured to determine that a mutual calibration factor acquired this time is valid when a difference between the mutual calibration factor acquired this time and a mutual calibration factor acquired at a previous time is within a second ratio of the mutual calibration factor acquired at the previous time, and the quantitative value confirmation unit is configured to determine that radioactive concentration of the reference object to be measured calculated this time is valid when a difference between the calculated radioactive concentration of the reference object to be measured and a quantitative value of radioactive concentration of the reference object to be measured acquired in advance is within a third ratio of the quantitative value of the radioactive concentration of the reference object to be measured acquired in advance. 
     
     
       7. The nuclear medical diagnosis apparatus according to  claim 6 , wherein
 the normalization unit registers the normalization factor when it is determined that the normalization factor is valid, 
 the calibration unit registers the mutual calibration factor when it is determined that the mutual calibration factor is valid, and 
 the quantitative value confirmation unit registers the calculated radioactive concentration of the reference object to be measured when it is determined that the calculated radioactive concentration of the reference object to be measured is valid. 
 
     
     
       8. The nuclear medical diagnosis apparatus according to  claim 1 , further comprising:
 a hangar that stores the reference object to be measured for maintenance; and 
 a carrying portion that carries the reference object to be measured for maintenance, wherein 
 the carrying portion carries the reference object to be measured for maintenance to a measurement area before the reference data is acquired by the data acquisition unit and stores the reference object to be measured for maintenance in the hangar after the reference data is acquired. 
 
     
     
       9. A nuclear medical diagnosis apparatus comprising:
 a plurality of detectors that detects annihilation radiation emitted from a reference object to be measured; and 
 a controller that acquires reference data of the reference object to be measured based on a result of detecting, by the plurality of detectors, the annihilation radiation emitted from the reference object to be measured, acquires a normalization factor for normalizing deviations of detection efficiencies among the plurality of detectors based on the reference data, acquires a mutual calibration factor for calibrating a pixel value of an image of the reference object to be measured acquired based on at least apart of the reference data used for acquisition of the normalization factor to radioactive concentration of the reference object to be measured, and compares radioactive concentration of the reference object to be measured calculated based on at least a part of the reference data used for acquisition of the normalization factor with a quantitative value of the radioactive concentration of the reference object to be measured. 
 
     
     
       10. A method for routine maintenance and inspection of a nuclear medical diagnosis apparatus, the method comprising:
 acquiring reference data of a reference object to be measured based on a result of detecting, by a plurality of detectors, annihilation radiation emitted from the reference object to be measured; 
 acquiring a normalization factor for normalizing deviations of detection efficiencies among the plurality of detectors based on the reference data; 
 applying the normalization factor to at least a part of the reference data used for acquisition of the normalization factor to acquire a mutual calibration factor for calibrating a pixel value of a reconstructed image of the reference object to be measured to radioactive concentration of the reference object to be measured; and 
 comparing radioactive concentration of the reference object to be measured calculated from a pixel value of an image of the reference object to be measured acquired by applying each of the normalization factor and the mutual calibration factor to at least a part of the reference data used for acquisition of the normalization factor with a quantitative value of the radioactive concentration of the reference object to be measured.